Hmmmm, never thought of that. I thought that was a solid piece of the yoke inserted back in there and that there would be room for the new threads. What about going to 5/8? The reason I want to do that is that I don't think they make 1/2 inch perches with a 5 or 9 degree angle so my spring shackles lay straight instead of cocked, due to the way the wishbones angle in at the rear.

Don